Formazan compounds and method of dyeing therewith

ABSTRACT

For dyeing (printing, for example) cellulose fibers with a reactive dye, a blue compound is greatly desired, the blue compound being capable of generating a product dyed in blue at excellent dyeing reproducibility and with good light fastness and superior fastness against chlorine water, involving less staining of white area. The invention relates to a formazan compound in a free acid form as represented by the following formula I, a dyeing method of cellulose fibers using the same and a final dyed product prepared by the method, characterized in that the compound, the method and the product are suitable so as to overcome the problem. 
     Formula I ##STR1## (wherein R represents hydrogen, sulfo group, hydroxyl group, halogen, a C1-C4 alkyl group, a C1-C4 alkoxyl group or carboxyl group; and M represents copper or nickel.)

TECHNICAL FIELD

The present invention relates to a formazan compound and a dyeing methodof fibers therewith. More specifically, the invention relates to adyeing method (printing method, in particular) of cellulose fibers in avivid blue color, with excellent various fastnesses, particularly lightfastness and fastness against chlorine water, with less staining ofwhite area and additionally at good reproducibility.

BACKGROUND OF THE INVENTION

In view of vivid hue, staining of white area and fastness, reactive dyesare frequently used for dyeing (printing, in particular) of cellulosefibers. Among them, reactive dyes having monochlorotriazino group as thereactive group are preferably used because the color pastes haveexcellent stability on standing. More specifically, as these reactivedyes, C. I. Reactive Orange 99 as yellow dyes, C. I. Reactive Red 3:1 asred dyes and C. I. Reactive Blue 49 and C. I. Reactive Blue 5 as bluedyes are exemplified.

The reactive dyes for use in printing of cellulose fibers are requiredto have the following quality properties.

1. Having good dyeing reproducibility, owing to the less dependency onthe conditions for intermediate drying after color pastes are printed onthe fibers. This property is dependent upon the affinity of a dye tocellulose fibers; when the affinity of a dye is too low, dyeingreproducibility is poor because the dependency on the conditions forintermediate drying is elevated (when a relatively long time is neededuntil the dyed fiber is dried up, the migration of the dye to the backface of the resulting printed cloth is so great that the depth of shadeon the surface of the printed cloth is reduced). Such dye is poor interms of reproducibility of a color dyed by combined dyeing of yellowdyes, red dyes or blue dyes between laboratory tests and fieldprocessing.

2. Having good dyeing reproducibility owing to the less dependency ofreactive dyes on the steaming conditions (steaming duration, inparticular) at a reacting and fixing process. This property is dependentupon the dye reactivity; it is required that reactive dyes have suchappropriate reactivity that stable reacting and fixing (high depth ofshade) can be attained even when the steaming conditions (steamingduration) vary. The property has a significant influence on the dyeingreproducibility at field.

3. Reducing in staining of white area (area with no color pastes printedthereon) and being able to obtain high-quality print by printingprocessing.

4. Having excellent fastness (especially light fastness and chlorinefastness) in a printed product and the long color life in the printedproduct.

From the standpoint of the quality properties required for such dyes forprinting, known blue dyes have serious drawbacks. Anthraquinone bluedyes such as C. I. Reactive Blue 49 and C. I. Reactive Blue 5 arecurrently used frequently, but these dyes exhibit such high dependencyon the conditions for intermediate drying as described above in 1 thatthe reproducibility between the result dyed at laboratory tests pand theresult dyed at fields is poor, leading to serious deterioration of theproductivity. Additionally, these dyes are seriously poor in terms ofthe fastness, particularly chlorine fastness as described above in 4, sothe color life of the resulting products is short.

JP-B-Hei5-21945 proposes a formazan blue dye as a means for improvingthe chlorine fastness, but the formazan compound described therein has anumber of drawbacks described below: t he compound is highly dependenton the steaming duration as described above in 2, leading to poor dyeingreproducibility at fields, with the resultant poor productivity alike;furthermore, the compound is poor in terms of reducing of the stainingof white area as described above in 3, so the resulting products dyed byprinting are of deteriorated quality.

It has been highly desired to develop a blue dye capable of satisfyingall of the quality properties described in 1 to 4 as required forreactive dyes to dye cellulose fibers, namely a blue dye with lowdependency on the conditions for intermediate drying and low dependencyon the steaming conditions and with good dyeing reproducibility,satisfactory reduced staining of white area and sufficient chlorinefastness, and with additional abilities enabling the improvement of theproductivity of printing process and the preparation of high-qualityproducts with long lives.

DISCLOSURE OF THE INVENTION

The present inventors have made serious investigations so as to overcomethe above-described problems. Consequently, the inventors have foundthat a formazan compound with 1-naphthylamino group substituted withsulfo group, as represented by the following formula I, is excellent interms of any of the aforementioned properties. Hence, the invention hasbeen achieved. More specifically, the invention relates to thosedescribed below in 1 to 5.

1. A formazan compound as represented by the formula I in a free acidform: ##STR2## wherein R represents hydrogen, sulfo group, hydroxylgroup, halogen, a C1-C4 alkyl group, a C1-C4 alkoxyl group or carboxylgroup; and M represents copper or nickel.

2. The formazan compound described above in 1, wherein R representshydrogen and M represents copper.

3. A dyeing method of cellulose fibers characterized by using theformazan compound described above in 1 or 2.

4. The dyeing method described above in 3, wherein the dyeing method isa printing method.

5. A product dyed by the dyeing method described above in 3 or 4.

BEST MODE FOR CARRYING OUT THE INVENTION

In the formazan compound as represented by the formula I in a free acidform, an example of R is hydrogen, sulfo group, hydroxyl group,chlorine, fluorine, bromine, methyl group, ethyl group, propyl group,n-butyl group, t-butyl group, methoxy group, ethoxy group, propoxygroup, butoxy group or carboxyl group etc.

So as to obtain a formazan compound represented by the formula I, aformazanamino compound represented by the formula II is produced by thefollowing method: ##STR3## wherein R and M individually represent thesame meanings as described above.

Namely, the formazanamino compound of the formula II can be prepared bycoupling diazotized 6-acetylamino-2-aminophenol-4-sulfo acid with5-sulfo-2-carboxyphenylhydrazones represented by the formula IV,followed by reaction with copper sulfate, nickel sulfate, copperchloride, nickel chloride or the like, and hydrolyzing the acetylaminogroup into amino group, wherein the 5-sulfo-2-carboxyphenylhydrazones ofthe formula IV are prepared from compounds represented by the formulaIII. ##STR4## (wherein R represents the same meaning as describedabove.) ##STR5##

By using the formazanamino compound thus prepared, the formazan compoundof the formula I can be synthetically prepared according to for examplemethod A or B described below.

A. The formazanamino compound represented by the formula II is allowedto react with one mole of 2,4,6-trichloro-1,3,5-triazine to prepare acondensate represented by the formula V or V', then allowing theresulting condensate to be condensed with one mole of1-naphthylamine-3,6,8-tri sulfo acid, to obtain the formazan compound ofthe formula I: ##STR6## wherein compounds represented by the formula Vand the formula V' are in a tautomeric relation.

These reactions are conducted in inert solvents such as water. Thereaction temperature is with no specific limitation. For example, thecondensation reaction between the formazanamino compound represented bythe formula II and 2,4,6-trichloro-1,3,5-triazine is effected, generallyat about 0° C. to about 15° C. and pH 2 to 7 for several hours, untilthe unchanged compound of the formula II does not any more remain.Continuously thereafter, the condensation between the compoundrepresented by the formula V or the formula V' and1-naphthylamine-3,6,8-tri sulfo acid is effected for example at about15° C. to about 60° C. and pH 1 to 7 for several hours, until theunchanged 1-naphthylamine-3,6,8-tri sulfo acid does not any more remain.

B. The compound of the following formula VI is prepared by thecondensation between 1-naphthylamine-3,6,8-tri sulfo acid and2,4,6-trichloro-1,3,5-triazine; and the formazanamino compoundrepresented by the formula II is allowed to react with one mole of theresulting compound represented by the formula VI. ##STR7##

These reactions are usually coducted in inert solvents such as water.For example, the condensation reaction between 1-naphthylamine-3,6,8-trisulfo acid and 2,4,6-trichloro-1,3,5-triazine is effected, at 0° C. to15° C. and pH 1 to 7 for several hours, until the1-naphthylamine-3,5,6,8-tri sulfo acid does not remain any more. Thefollowing reaction between the compound represented by the formula IIand the compound represented by the formula VI is effected for exampleat 15° C. to 60° C. and pH 3 to 8 for several hours, until the unchangedcompound of the formula II does not any more remain.

Because it is more or less difficult to separate the objective compoundby applying routine separation methods such as salting-out method oracid deposition method to the thus obtained reaction solution,preferably, the reaction solution is prepared as it is as a liquidproduct or the reaction solution is prepared as a liquid product bysubjecting the reaction solution to a desalting process and aconcentration process and adding then a solubilizer or a stabilizer suchas urea, alkanolamine, alkylamine, and ε-caprolactam to the resultingsolution. Alternatively, the reaction solution can be spray dried as itis.

The thus obtained formazan compound of the formula I is present in theform of a free acid or a salt thereof; the salt includes alkaashtalsalts, alkaline earth metal salts, alkylamine salts, and alkanolaminesalts thereof. Preferable are the sodium salt, potassium salt andlithium salt thereof, in particular. Each salt of the compound of theformula I can be prepared by separating the objective compound in theform of a free acid from the reaction solution and subjecting then thecompound to treatment with an alkali agent, or by using, as each rawmaterial, a desired salt thereof.

The formazan compound represented by the formula I in accordance withthe invention is suitable for dyeing natural celluloses such as cottonand linen, regenerated celluloses such as rayon and polynosic, lyocell,and blended yarn fabrics of these fibers with other fibers; and thedyeing method includes usual dyeing methods with general reactive dyessuch as printing, padding dyeing, and additionally dip dyeing. Dyedfibers or cloth can be obtained by dyeing fibers or cloth with a dyecomposition containing the formazan compound represented by the formulaI by routine methods such as dipping , printing or padding and, ifnecessary, fixing the dye through thermal treatment such as drying underheating, steaming, and dry heat treatment if necessary in the presenceof auxiliary dyeing agents or thickeners. Typical methods thereof arenow described in more detail.

By printing method, first, a color paste is prepared by adding a dye,urea, an acid binder, and an anti-reduction agent (for example, PolymineL New; product of Nippon Kayaku, Co. Ltd.) to a stock paste such assodium alginate and an emulsion paste; subsequently printing the colorpaste on fibers (materials to be dyed) and subjecting then the fibers tointermediate drying (for example at 100 to 110° C. for 2 to 3 minutes)and thereafter to a steaming process (for example at 100 to 103° C. for5 to 10 minutes) or a dry heat process, the dye can be fixed thereon.

For applying the compound of the present invention to padding dyeingmethod (continuous dyeing); a pad solution is prepared, comprising adye, an acid binder, a penetrating agent (for example, Succinol CHK;manufactured by Senka, Co. Ltd.), urea as a dye dissolving agent, ureaas a water-retentive agent, and sodium alginate as amigration-preventing agent; then, fibers are subjected to paddingtreatment, followed by intermediate drying (for example at 100 to 110°C. for 2 to 3 minutes) and a subsequent dry heat process (for example at150 to 170° C. for 2 to 3 minutes), and the dye is fixed thereon.

Examples of the acid binder for use in the aforementioned methods aresodium hydrogencarbonate, sodium carbonate, sodium triphosphate, sodiummetaphosphate, sodium ortho- or metasilicate, and sodium hydroxide etc.

When the formazan compound of the present invention is used in theprinting method, a stable depth of shade is obtained because a variationof the depth of shade is small, despite a variation of intermediatedrying conditions and steaming duration, and the dyeing reproducibilityis excellent. Additionally, the high-quality printed products can beobtained because of less staining of white area. In recent years,furthermore, attention has been focused on a printing method reducingamount of urea, which contains nitrogen, from the standpoint of therelation with the phenomenon of eutrophication in closed water areas dueto nitrogen and phosphorus. Insofar, the use of a massive amount of ureagiving an appropriate amount of water to fibers is indispensable for thepurpose of reaction and fixing of reactive dyes on cellulose fiberseffectively. By the use of the compound of the present invention,however, printing by a method with urea reduction is achieved. When thecompound of the present invention is used for padding dyeing method,furthermore, it is a characteristic that the color variation between thestart and end of the roll in the finished dyed cloth is less, too.

The formazan compound of the present invention, when used for dip dyeingmethod other than printing method and padding dyeing method, can providesimilar good result.

The dyed products obtained by these dyeing methods in accordance withthe invention exhibit a fast and vivid blue hue with excellent lightfastness and fastness against chlorine water.

The same effects can be yielded, when two or more types of the compoundof the present inventions are mixed together and used or when thecompound of the present invention is used as a blend with the yellowdyes and red dyes and others currently for common use.

The invention is now described in more detail in the following examplesbut is not limited thereto. In the examples, the terms part(s) and %mean part(s) by weight or % by weight, respectively; and in theindividual formulas, the sulfo group is represented in the free form.

EXAMPLE 1

Synthesis of the compound of the present invention represented by thefollowing formula VII. ##STR8##

To a solution comprising 10 parts of water, 10 parts of ice, 0.5 part ofan aqueous 10% Liponox NA (trade name; a dispersant; manufactured byLion, Co.) was added 3.8 parts of cyanuric chloride under agitation.After 30-min agitation (of the resulting suspension), a solution of 7.7parts of 1-naphthylamine-3,6,8-tri sulfo acid dissolved in 20 parts ofwater was poured and added to the suspension over 30 minutes while thesuspension was retained below 10° C. While the resulting mixture wasretained at pH 2 to 4 by using an aqueous 10% soda ash solution at about10° C., the reaction was continued for 3 hours under agitation. Thereaction solution was added to a solution of 11.9 parts of theformazanamino compound of the formula VIII dissolved in 100 parts ofwater. ##STR9##

The temperature of the mixture was raised, and at a temperature of 30 to40° C., then, reaction was continued for 3 hours, while the mixture wasretained at pH 6 to 8 with an aqueous 10% soda ash solution.Furthermore, the reaction solution was subjected to membrane treatmentfor desalting and concentration, whereby 120 parts of a dye solutioncontaining 18% of the compound of the formula VII mentioned above wasobtained (λmax 610 nm in water).

EXAMPLE 2

A color paste of a composition ratio shown in the following table of 100parts was prepared.

                  TABLE 1                                                         ______________________________________                                        Compound of Example 1 (dye solution)                                                                8        parts                                            Urea 10 parts                                                                 Sodium hydrogencarbonate 2 parts                                              Polymine L New (Note 1) 1.5 parts                                             Warm water 28.5 parts                                                         Stock paste (Note 2) 50 parts                                                 Total 100 parts                                                             ______________________________________                                         Note 1: Polymine L New; trade name; antireduction agent; manufactured by      Nippon Kayaku Co. Ltd.                                                        Note 2: Stock paste: Snow Algin M (trade name) (a sodium alginate stock       paste comprising 5 parts of a sodium alginate and 95 parts of water),         manufactured by Fuji Chemicals, Co. Ltd.                                 

The color paste was printed on mercerized cotton broad weighed 50 g,followed by intermediate drying at 100° C. for 3 minutes and subsequentsteaming process in saturated steam at 100° C. for 8 minutes, forreacting and fixing of the dye.

Then, the mercerized cotton broad was washed in water and warm water andsubjected to soaping in a boiling water bath of 1000 g containing 2 g ofMonogen (trade name; anion surfactant manufactured by DAI-ICHI KOGYOSEIYAKU, CO. Ltd.) for 15 minutes, followed by washing in water. Theresulting printed product exhibited a vivid blue with excellent lightfastness and fastness against chlorine water and staining of white areais almost nothing.

EXAMPLE 3 to 10

By using compounds produced according to Examples 1 and 2, cotton wasdyed (by printing). Tables 2 to 4 show the structural formulas of thesynthesized compounds, and the hue of cotton dyed with the compounds,together with the λmax in water of the compounds.

                                      TABLE 2                                     __________________________________________________________________________    Example                                                                         No. Structural formula Hue max (nm)                                         __________________________________________________________________________      3                                                                                                                                      blue 609                                                                      - 4                                                                           blue 595                                                                      - 5                                                                           blue 609           __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________    Example                                                                         No. Structural formula Hue max (nm)                                         __________________________________________________________________________      6                                                                                                                                      blue 608                                                                      - 7                                                                           blue 600                                                                      - 8                                                                           blue 609           __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________    Example                                                                         No. Structural formula Hue max (nm)                                         __________________________________________________________________________       9                                                                                                                                     blue 610                                                                      - 10                                                                          blue 610           __________________________________________________________________________

EXAMPLE 11

According to the printing method described in Example 2, rayon muslinwas printed, using 5 parts of the compound of Example 1. The resultingdyed product exhibited a vivid blue with excellent light fastness andfastness against chlorine water. Even when the steaming duration waschanged to 4, 8 and 16 minutes, the depth of shade was only slightlychanged.

EXAMPLE 12

A padding solution was prepared, using 40 parts of the compound ofExample 1, 20 parts of sodium carbonate, 150 parts of urea, one part ofSnow Algin (trade name) and 1000 parts of pure water; mercerized cottonbroad of 50 g was subjected to padding process at a squeezing ratio of70%, followed by intermediate drying at 100° C. for 3 minutes. Then, themercerized cotton broad was subjected to dry heat process at 160° C. for3 minutes, for reacting and fixing the dye on the cotton broad.Thereafter, the cotton broad was washed in water and washed in warmwater, and was then subjected to soaping in a boiling water bath of 1000g containing 2 parts of Monogen (trade name; anion surfactant;manufactured by DAI-ICHI KOGYO SEIYAKU, CO. Ltd) for 15 minutes,followed by additional washing in water.

The resulting dyed product exhibited a vivid blue with excellent lightfastness and good chlorine fastness.

Comparative Tests

The compound of the present invention (Example 1) and 5 types of knowndyes (C. I. Reactive Blue 49 as Comparative Example 1, C. I. ReactiveBlue 5 as Comparative Example 2, the compound of Example 17 described inJP-B-Hei5-21945 as Comparative Example 3, the compound of Example 19described in the same gazette as Comparative Example 4, and the compoundof Example 25 described in the same gazette as Comparative Example 5)were compared to each other, regarding the properties thereof forprinting according to the following methods.

A. Common Printing Method

100 parts of individual color pastes of the following compositions inTable 5 are prepared.

                  TABLE 5                                                         ______________________________________                                        Each compound (dye)                                                                           X           parts (Note 3)                                      Urea 10 parts                                                                 Sodium hydrogencarbonate 2 parts                                              Polymine L New (Note 1) 1.5 parts                                             Warm water (36.5-X) parts                                                     Stock paste (Note 2) 50 parts                                                 Total 100 parts                                                             ______________________________________                                         Note 1: Polymine L New: trade name; antireduction agent; manufactured by      Nippon Kayaku Co. Ltd.                                                        Note 2: Stock paste: Snow Algin M (trade name) (a sodium alginate stock       paste comprising 5 parts of a sodium alginate and 95 parts of water),         manufactured by Fuji Chemical, Co. Ltd.                                       Note 3: Depending on the test for each of 4 items described below, the        amount of each compound (dye) varies; therefore, the amount is herein         expressed generally as X parts. The amount of each compound (dye) at each     test was specifically described in the corresponding part hereinbelow         (test conditions for each test item).                                    

The color paste was printed on mercerized cotton broad of 50 parts,followed by intermediate drying at 100° C. for 3 minutes and subsequentsteaming process in saturated steam at 100° C. for 8 minutes, forreacting and fixing of the dye thereon.

Then, the mercerized cotton broad was washed in water and, washed inwarm water and was then subjected to soaping in a boiling water bath of1000 g containing 2 parts of an anion surfactant for 15 minutes,followed by washing in water.

B. Test Conditions of Each Test Item

1. Dependency on intermediate drying conditions

Using 4 parts of the compound of Example 1 [the compounds of ComparativeExamples 1 to 5 were individually used at their amounts corresponding tothe same OD (optical density) values as that of the compound of Example1] and 2 parts of C. I. Reactive Orange 99, printed products wereprepared by dyeing according to the common printing method, except forthe two levels of the intermediate drying conditions, namely 100° C. for3 minutes and 40° C. for one hour.

The color change of the surface each of the resulting printed productsand the strike-through state (degree of dye migration to the backsurface of the printed products) as for reference were visuallydetermined, and the results are shown in Table 6. The assessment resultsare ranked according to the following criteria.

Overall Assessment:

o: under the two-level drying conditions, the color of the surface(surface color) is identical, with low strike-through state (lowdependency on intermediate drying conditions; good state).

x: under the two-level drying conditions, the color of the surface(surface color) under the latter conditions is apparently changed,involving high strike-through state, compared with the surface colorunder the former conditions (high dependency on intermediate dryingconditions; poor state).

2. Dependency on steaming duration (ST dependency)

Except for the use of 4 parts of the compound of Example 1 (thecompounds of Comparative Examples 1 to 5 were individually used at theiramounts corresponding to the same OD values as that of 4 parts of thecompound of Example 1) and that the steaming duration varied from 2minutes to 4 minutes, 8 minutes and 16 minutes, individual printedproducts were prepared by dyeing according to the common printingmethod.

The reflectance of each of the resulting printed products was measuredwith a spectrophotometer CE-3100 manufactured by Macbeth Co., todetermine the Q-Total value (optical density). Table 6 shows the ratio(QT ratio) of the Q-Total value to the Q-Total value determined for8-min steaming and defined as a base line value 100. The assessmentresults marked with o or x are determined according to the followinggrades.

Assessment:

o: QT ratio above 80, when the steaming duration was any one of 2, 4,and 16 minutes.

x: compound with at least one QT ratio below 79, when the steamingduration was one of 2, 4 and 16 minutes.

3. Degree of staining of white area (stained degree of white area)

Except for the use of 8 parts of the compound of Example 1 (thecompounds of Comparative Examples 1 to 5 were individually used at theiramounts corresponding to the same OD values as that of 8 parts of thecompound of Example 1), processes up to steaming process were conductedaccording to the common printing method; then, the following washingprocess was performed to determine the stained degrees of white area(white cloth) during the process, on the basis of the white cloth priorto the washing process, according to the Gray Scale for stainingaccording to JIS L 0805.

Washing process

In 100 parts of pure water were placed 2.5 parts of printed (steamingprocessed) cloth and 2.5 parts of mercerized cotton broad (white cloth),for 10-min treatment at 30° C. Thereafter, the printed cloth and thewhite cloth were taken out and dewatered, which were then placed in 100parts of fresh pure water again, for 10-min treatment at 90° C.,followed by dewatering and drying.

The stained degree of the mercerized cotton broad, (white cloth) wasdetermined on the basis of white cloth, by the Gray Scale for stainingaccording to JIS L 0805. The results are shown on the determined gradesmarked with o and x in Table 6. Larger grades indicate better results(with small staining degrees).

Grades of 4 or more are marked with o; and grades of 3 or less aremarked with x.

4. Fastness against chlorine water

Printed products were obtained by using 6 parts of the compound ofExample 1 (the compounds of Comparative Examples 1 to 5 wereindividually used at their amounts corresponding to the same OD valuesas that of 6 parts of the compound of Example 1) according to the commonprinting method.

According to the high-level test of Fastness against Chlorine Water (ateffectivechlorineof 20 ppm) of JIS L 0884, the resulting printed clothwas tested of its fastness against chlorine water. The results are shownin Table 6, along with the assessment results represented with gradesand marked with o and x. Larger grades indicate better results (lesscolor change or discoloration).

The aforementioned individual results are collectively shown in Table 6.

As is apparently shown in Table 6, C. I. Reactive Blue 49 (the compoundof Comparative Example 1) and C. I. Reactive Blue 5 (the compound ofComparative Example 2) currently for frequent use are with too low dyeaffinity, so these dyes cause high strike-through state to reduce theblue depth of shade on the surface when the resulting dyed products aredried at a relatively low temperature (corresponding to the dryingcondition for test dyeing), leading to considerable change of the colorto a yellowish hue.

Thus, the reproducibility (reproducibility between test dyeing and fieldprocessing) is poor. Additionally, these dyes are poor in terms offastness against chlorine water.

On the other hand, the compounds (dyes) of Examples 17, 19 and 25 asdescribed in JP-B-Hei5-21945 are poor, because these compounds causelarge variations of the depth of shade, following the change of thesteaming duration, with poor reproducibility (in this case,reproducibility between inter-site processes or inter-steaming machines)and additionally with severe staining of white area.

Only the compound of Example 1 has low dependency on both theintermediate drying conditions and steaming duration, so the compoundcan give a stable depth of shade with excellent dyeing reproducibility,and both with less staining of white area and with good fastness againstchlorine water.

Hence, it is apparently shown that the compound of the present inventionis a blue dye capable of improving the productivity of printingprocessing and obtaining high-quality products with a long life.

                                      TABLE 6                                     __________________________________________________________________________            Dependency on intermediate drying                                       conditions  Chlorine water fastness                                                       strike-through                                                                        general                                                                             ST dependency                                                                            White area staining                                                                      high-level                  Compounds                                                                             surface color                                                                       state   assessment                                                                          QT ratio                                                                           assessment                                                                          grades                                                                             assessment                                                                          test values                                                                         assessment            __________________________________________________________________________    Compound of                                                                           identical                                                                           low     ◯                                                                       94   ◯                                                                       4    ◯                                                                       3-4   ◯                                                                  Example 1    100           *(100)                                                                        99                                                                        Compound of considerably high strike- X 83 ◯ 4-5 .largecircl                                                            e. 1-2 X                Comparative yellowish through of  94                                          Example 1  bluish hue  *(100)                                                     100                                                                       Compound of considerably high strike- X 85 ◯ 4-5 .largecircl                                                            e. 2 X                  Comparative yellowish through of  95                                          Example 2  bluish hue  *(100)                                                     99                                                                        Compound of identical low ◯ 106  X 2-3 X 3-4 ◯                                                               Comparative                                                                  101                     Example 3    *(100)                                                               73                                                                        Compound of identical low ◯ 107  X 2-3 X 4 ◯                                                                 Comparative                                                                  101                     Example 4    *(100)                                                               72                                                                        Compound of identical low ◯ 68 X 2-3 X 4 ◯                                                                   Comparative                                                                  90                      Example 5    *(100)                                                               98                                                                      __________________________________________________________________________

Notes:

Supplementary description of each item in Table 6

1. Dependency on intermediate drying conditions Hue and strike-throughstate of product dried at 40° C. for one hour, as judged on the basis ofthe hue and strike-through state of product dried at 100° C. for 3minutes.

2. ST dependency

QT ratios are expressed as the ratios in % of Q-Total values at steamingdurations of 2, 4 and 16 minutes to the Q-Total value (represented as*(100) in the table) at a steaming duration of 8 minutes; the ratios arein the sequential order for 2, 4 and 16 minutes from the top.

3. White area staining

Grades are shown according to the Gray Scale for Staining according toJIS L 0805.

4. Chlorine water fastness

Grades are based on the values at the tests of fastness against chlorinewater according to the high-level test (at effective chlorine of 20 ppm)of the Fastness against Chlorine Water of JIS L 0884.

5. Compound of Comparative Example 1

C. I. Reactive Blue 49.

6. Compound of Comparative Example 2

C. I. Reactive Blue 5.

7. Compound of Comparative Example 3

Compound of Example 17 of JP-B-Hei5-21945.

8. Compound of Comparative Example 4

Compound of Example 19 of JP-B-Hei5-21945.

9. Compound of Comparative Example 5

Compound of Example 25 of JP-B-Hei5-21945.

Industrial Applicability

The compound of the present invention can dye cellulose fibers in avivid blue with high dyeing reproducibility, and the resulting dyedproduct characteristically has excellent light fastness and excellentfastness against chlorine water, with less staining of white area.Accordingly, the inventive dye is very useful for improving theproductivity of dyeing processing and is utilized for producing dyedproducts with high quality and a long life.

We claim:
 1. A formazan compound in a free acid form as represented bythe formula I: ##STR18## wherein R represents hydrogen, sulfo group,hydroxyl group, halogen, a C1-C4 alkyl group, a C1-C4 alkoxyl group orcarboxyl group; and M represents copper or nickel.
 2. A formazancompound according to claim 1, wherein R represents hydrogen and Mrepresents copper.
 3. A dyeing method of cellulose fibers characterizedby using a formazan compound according to claim 1 or
 2. 4. A dyeingmethod according to claim 3, wherein the dyeing method is a printingmethod.
 5. A product dyed by a dyeing method according to claim 3 or 4.